<!--
Copyright (c) 2014 The Polymer Project Authors. All rights reserved.
This code may only be used under the BSD style license found at http://polymer.github.io/LICENSE.txt
The complete set of authors may be found at http://polymer.github.io/AUTHORS.txt
The complete set of contributors may be found at http://polymer.github.io/CONTRIBUTORS.txt
Code distributed by Google as part of the polymer project is also
subject to an additional IP rights grant found at http://polymer.github.io/PATENTS.txt
-->

<!--
`paper-toggle-button` provides a ON/OFF switch that user can toggle the state
by tapping or by dragging the swtich.

Example:

    <paper-toggle-button></paper-toggle-button>

Styling toggle button:

To change the ink color for checked state:

    paper-toggle-button::shadow paper-radio-button::shadow #ink[checked] {
      color: #4285f4;
    }
    
To change the radio checked color:
    
    paper-toggle-button::shadow paper-radio-button::shadow #onRadio {
      background-color: #4285f4;
    }
    
To change the bar color for checked state:

    paper-toggle-button::shadow #toggleBar[checked] {
      background-color: #4285f4;
    }
    
To change the ink color for unchecked state:

    paper-toggle-button::shadow paper-radio-button::shadow #ink {
      color: #b5b5b5;
    }
    
To change the radio unchecked color:
    
    paper-toggle-button::shadow paper-radio-button::shadow #offRadio {
      border-color: #b5b5b5;
    }

To change the bar color for unchecked state:

    paper-toggle-button::shadow #toggleBar {
      background-color: red;
    }

@group Paper Elements
@element paper-toggle-button
@homepage github.io
-->

<link rel="import" href="../paper-radio-button/paper-radio-button.html">

<polymer-element name="paper-toggle-button" attributes="checked" touch-action="pan-y" role="button" aria-pressed="false" tabindex="0">
<template>

  <link rel="stylesheet" href="paper-toggle-button.css">

  <div id="toggleContainer">
  
    <div id="toggleBar" checked?="{{checked}}"></div>
  
    <paper-radio-button id="toggleRadio" toggles checked="{{checked}}"
        on-trackstart="{{trackStart}}" on-track="{{track}}" on-trackend="{{trackEnd}}"></paper-radio-button>
    
  </div>

</template>
<script>

  Polymer('paper-toggle-button', {
    
    /**
     * Fired when the checked state changes.
     *
     * @event change
     */

    /**
     * Gets or sets the state, `true` is checked and `false` is unchecked.
     *
     * @attribute checked
     * @type boolean
     * @default false
     */
    checked: false,

    trackStart: function(e) {
      this._w = this.$.toggleBar.offsetLeft + this.$.toggleBar.offsetWidth;
      e.preventTap();
    },

    track: function(e) {
      this._x = Math.min(this._w, 
          Math.max(0, this.checked ? this._w + e.dx : e.dx));
      this.$.toggleRadio.classList.add('dragging');
      var s =  this.$.toggleRadio.style;
      s.webkitTransform = s.transform = 'translate3d(' + this._x + 'px,0,0)';
    },

    trackEnd: function() {
      var s =  this.$.toggleRadio.style;
      s.webkitTransform = s.transform = null;
      this.$.toggleRadio.classList.remove('dragging');
      this.checked = Math.abs(this._x) > this._w / 2;
    },

    checkedChanged: function() {
      this.setAttribute('aria-pressed', Boolean(this.checked));
      this.fire('change');
    }

  });

</script>
</polymer-element>
